Analytical study of heating of dielectric material in microwave field

The results of an analytical study of the heating of a dielectric material in a microwave field are presented. Dependences for the calculation of local temperatures were obtained for solving the problems of thermal conductivity in the body under the conditions of the action of two heat sources (positive, caused by the transformation of the energy of the electromagnetic field into thermal energy, and negative, determined by evaporation) for a semibounded massive under boundary conditions of the first and third kind. The dependencies are approved in the calculation of the temperature for both the conditions of exclusively heating in the microwave field and taking into account the removal of moisture in the microwave drying process. The influence of the specific power of internal sources, initial temperature, and heat transfer coefficient on heating kinetics is analyzed. For boundary conditions of the first kind, the correctness of solutions is noted, provided that the temperature of the material does not exceed the surface temperature by more than 12%. An analysis of the results of calculating the average body temperature under kind III boundary conditions showed a satisfactory agreement between the calculated and experimental data obtained in the study of drying oats in a microwave field. It is shown that the areas of applicability of analytical dependencies are limited by the values of the power of internal heat sources and heat transfer coefficients.